/*

 * Copyright (C) the libgit2 contributors. All rights reserved.

 *

 * This file is part of libgit2, distributed under the GNU GPL v2 with

 * a Linking Exception. For full terms see the included COPYING file.

 */

#include "tree-cache.h"

#include "pool.h"

#include "tree.h"

static git_tree_cache *find_child(

	const git_tree_cache *tree, const char *path, const char *end)

{

	size_t i, dirlen = end ? (size_t)(end - path) : strlen(path);

	for (i = 0; i < tree->children_count; ++i) {

		git_tree_cache *child = tree->children[i];

		if (child->namelen == dirlen && !memcmp(path, child->name, dirlen))

			return child;

	}

	return NULL;

}

void git_tree_cache_invalidate_path(git_tree_cache *tree, const char *path)

{

	const char *ptr = path, *end;

	if (tree == NULL)

		return;

	tree->entry_count = -1;

	while (ptr != NULL) {

		end = strchr(ptr, '/');

		if (end == NULL) /* End of path */

			break;

		tree = find_child(tree, ptr, end);

		if (tree == NULL) /* We don't have that tree */

			return;

		tree->entry_count = -1;

		ptr = end + 1;

	}

}

const git_tree_cache *git_tree_cache_get(const git_tree_cache *tree, const char *path)

{

	const char *ptr = path, *end;

	if (tree == NULL) {

		return NULL;

	}

	while (1) {

		end = strchr(ptr, '/');

		tree = find_child(tree, ptr, end);

		if (tree == NULL) /* Can't find it */

			return NULL;

		if (end == NULL || *end + 1 == '\0')

			return tree;

		ptr = end + 1;

	}

}

static int read_tree_internal(git_tree_cache **out,

			      const char **buffer_in, const char *buffer_end,

			      git_pool *pool)

{

	git_tree_cache *tree = NULL;

	const char *name_start, *buffer;

	int count;

	buffer = name_start = *buffer_in;

	if ((buffer = memchr(buffer, '\0', buffer_end - buffer)) == NULL)

		goto corrupted;

	if (++buffer >= buffer_end)

		goto corrupted;

	if (git_tree_cache_new(&tree, name_start, pool) < 0)

		return -1;

	/* Blank-terminated ASCII decimal number of entries in this tree */

	if (git__strntol32(&count, buffer, buffer_end - buffer, &buffer, 10) < 0)

		goto corrupted;

	tree->entry_count = count;

	if (*buffer != ' ' || ++buffer >= buffer_end)

		goto corrupted;

	 /* Number of children of the tree, newline-terminated */

	if (git__strntol32(&count, buffer, buffer_end - buffer, &buffer, 10) < 0 || count < 0)

		goto corrupted;

	tree->children_count = count;

	if (*buffer != '\n' || ++buffer > buffer_end)

		goto corrupted;

	/* The SHA1 is only there if it's not invalidated */

	if (tree->entry_count >= 0) {

		/* 160-bit SHA-1 for this tree and it's children */

		if (buffer + GIT_OID_RAWSZ > buffer_end)

			goto corrupted;

		git_oid_fromraw(&tree->oid, (const unsigned char *)buffer);

		buffer += GIT_OID_RAWSZ;

	}

	/* Parse children: */

	if (tree->children_count > 0) {

		unsigned int i;

		tree->children = git_pool_malloc(pool, tree->children_count * sizeof(git_tree_cache *));

		GITERR_CHECK_ALLOC(tree->children);

		memset(tree->children, 0x0, tree->children_count * sizeof(git_tree_cache *));

		for (i = 0; i < tree->children_count; ++i) {

			if (read_tree_internal(&tree->children[i], &buffer, buffer_end, pool) < 0)

				goto corrupted;

		}

	}

	*buffer_in = buffer;

	*out = tree;

	return 0;

 corrupted:

	giterr_set(GITERR_INDEX, "corrupted TREE extension in index");

	return -1;

}

int git_tree_cache_read(git_tree_cache **tree, const char *buffer, size_t buffer_size, git_pool *pool)

{

	const char *buffer_end = buffer + buffer_size;

	if (read_tree_internal(tree, &buffer, buffer_end, pool) < 0)

		return -1;

	if (buffer < buffer_end) {

		giterr_set(GITERR_INDEX, "corrupted TREE extension in index (unexpected trailing data)");

		return -1;

	}

	return 0;

}

static int read_tree_recursive(git_tree_cache *cache, const git_tree *tree, git_pool *pool)

{

	git_repository *repo;

	size_t i, j, nentries, ntrees;

	int error;

	repo = git_tree_owner(tree);

	git_oid_cpy(&cache->oid, git_tree_id(tree));

	nentries = git_tree_entrycount(tree);

	/*

	 * We make sure we know how many trees we need to allocate for

	 * so we don't have to realloc and change the pointers for the

	 * parents.

	 */

	ntrees = 0;

	for (i = 0; i < nentries; i++) {

		const git_tree_entry *entry;

		entry = git_tree_entry_byindex(tree, i);

		if (git_tree_entry_filemode(entry) == GIT_FILEMODE_TREE)

			ntrees++;

	}

	cache->children_count = ntrees;

	cache->children = git_pool_mallocz(pool, ntrees * sizeof(git_tree_cache *));

	GITERR_CHECK_ALLOC(cache->children);

	j = 0;

	for (i = 0; i < nentries; i++) {

		const git_tree_entry *entry;

		git_tree *subtree;

		entry = git_tree_entry_byindex(tree, i);

		if (git_tree_entry_filemode(entry) != GIT_FILEMODE_TREE) {

			cache->entry_count++;

			continue;

		}

		if ((error = git_tree_cache_new(&cache->children[j], git_tree_entry_name(entry), pool)) < 0)

			return error;

		if ((error = git_tree_lookup(&subtree, repo, git_tree_entry_id(entry))) < 0)

			return error;

		error = read_tree_recursive(cache->children[j], subtree, pool);

		git_tree_free(subtree);

		cache->entry_count += cache->children[j]->entry_count;

		j++;

		if (error < 0)

			return error;

	}

	return 0;

}

int git_tree_cache_read_tree(git_tree_cache **out, const git_tree *tree, git_pool *pool)

{

	int error;

	git_tree_cache *cache;

	if ((error = git_tree_cache_new(&cache, "", pool)) < 0)

		return error;

	if ((error = read_tree_recursive(cache, tree, pool)) < 0)

		return error;

	*out = cache;

	return 0;

}

int git_tree_cache_new(git_tree_cache **out, const char *name, git_pool *pool)

{

	size_t name_len;

	git_tree_cache *tree;

	name_len = strlen(name);

	tree = git_pool_malloc(pool, sizeof(git_tree_cache) + name_len + 1);

	GITERR_CHECK_ALLOC(tree);

	memset(tree, 0x0, sizeof(git_tree_cache));

	/* NUL-terminated tree name */

	tree->namelen = name_len;

	memcpy(tree->name, name, name_len);

	tree->name[name_len] = '\0';

	*out = tree;

	return 0;

}

static void write_tree(git_buf *out, git_tree_cache *tree)

{

	size_t i;

	git_buf_printf(out, "%s%c%"PRIdZ" %"PRIuZ"\n", tree->name, 0, tree->entry_count, tree->children_count);

	if (tree->entry_count != -1)

		git_buf_put(out, (const char *) &tree->oid, GIT_OID_RAWSZ);

	for (i = 0; i < tree->children_count; i++)

		write_tree(out, tree->children[i]);

}

int git_tree_cache_write(git_buf *out, git_tree_cache *tree)

{

	write_tree(out, tree);

	return git_buf_oom(out) ? -1 : 0;

}